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<html xmlns="http://www.w3.org/1999/xhtml">

<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>累加按钮，自加1</title>
    <style>
        input {
            font: 12px arial;
            cursor: pointer;
            padding: 0 10px;
        }
    </style>
    <script>
        window.onload = function () {
            var aBtn = document.getElementsByTagName("input")[0];
            var i = 0;
            aBtn.onclick = function () {
                aBtn.value = ++i;
                alert(i)
            }
        }
    </script>
</head>

<body>
    <input type="button" value="0" />
</body>

</html>